1. Field of the Invention
The present invention relates to improvements in a bushing assembly, for example, for use in automotive vehicles, and more particularly to the bushing assembly of the type wherein a seal rubber is disposed between an inner cylinder member and a rigid sleeve member disposed between the inner cylinder member and an outer cylinder member in order to accomplish seal, in which an elastic member is disposed between the rigid sleeve member and the outer cylinder member while a sliding member is provided between the rigid sleeve and the inner cylinder member to reduce a torsion spring effect of the elastic member.
2. Description of the Prior Art
Bushing assemblies have been used, for example, at joints between an upper control arm of a double wishbone type suspension and a vehicle body in an automotive vehicle. Such a bushing assembly usually includes inner and outer cylinder members which are coaxial and spaced from each other. The inner cylinder member is connected to an upper control arm side while the outer cylinder member is connected to a vehicle body side. An elastic member is disposed between the inner and outer cylinder members to absorb a relative displacement of the inner and outer cylinder members in the radial direction. Additionally, a sliding member is provided between the elastic member and the inner cylinder member to make possible a relative rotation around the axis between the inner and outer cylinder members.
A bushing assembly of this type is disclosed, for example, in Japanese Patent Provisional Publication No. 61-127934. This bushing assembly is provided with a rigid sleeve disposed between the elastic member and the sliding member. The rigid sleeve is formed with an outer flange including a radially outwardly extending section from which a cylindrical section extends axially. A seal rubber is provided inside the cylindrical section and in such a manner as to be brought into contact with the retainer member formed at the end section of the inner cylinder member and/or the outer peripheral surface of the sliding member, thereby to accomplish seal at least between it and the retainer member.
However, in such a conventional bushing assembly, the seal rubber is brought into contact with the inner cylinder member retainer member and the sliding member, and therefore there develops a larger friction therebetween thereby to obstruct a relative rotation between the inner and outer cylindr members. Additionally, since the seal rubber is relatively short and rigid, dimension error and relative displacement of the retainer member or the like cannot be effectively absorbed, so that an excess or a shortage in contact width of the seal rubber tends to be made thereby lowering seal durability and seal effect. Furthermore, even inf a slight amount of water and/or mud penetrates through the seal section of the seal rubber, it is liable to reach the sliding member thereby deteriorating the sliding member.